Showerhead electrode assembly in a capacitively coupled plasma processing apparatus

Abstract

A showerhead electrode assembly for use in a capacitively coupled plasma processing apparatus comprising a heat transfer plate. The heat transfer plate having independently controllable gas volumes which may be pressurized to locally control thermal conductance between a heater member and a cooling member such that uniform temperatures may be established on a plasma exposed surface of the showerhead electrode assembly.

What is claimed is: 
     
       1. A showerhead electrode assembly of a plasma processing chamber, comprising:
 a showerhead electrode; 
 a top plate configured to support the showerhead electrode; 
 a heater plate disposed between the top plate and the showerhead electrode; and 
 a heat transfer plate disposed between the showerhead electrode and the top plate, wherein the heat transfer plate comprises a plurality of independently controllable gas volumes such that a gas pressure within any given one of the plurality of independently controllable gas volumes does not affect another gas pressure within any other of the plurality of independently controllable gas volumes. 
 
     
     
       2. The showerhead electrode assembly of  claim 1 , wherein the heat transfer plate is disposed between the top plate and the heater plate. 
     
     
       3. The showerhead electrode assembly of  claim 1 , wherein the heat transfer plate is disposed between the heater plate and the showerhead electrode. 
     
     
       4. The showerhead electrode assembly of  claim 1 , wherein the independently controllable gas volumes have a radial configuration, a non-radial configuration, a hexagonally divided configuration, an octagonally divided configuration, or a quadrant divided configuration. 
     
     
       5. The showerhead electrode assembly of  claim 1 , wherein the heat transfer plate comprises sixteen radially extending independently controllable gas volumes wherein eight gas volumes are located in an inner region of the heat transfer plate and eight gas volumes are located in an outer region of the heat transfer plate, each independently controllable gas volume extending about 38 to 45° around the circumference of the heat transfer plate. 
     
     
       6. The showerhead electrode assembly of  claim 1 , wherein the heat transfer plate comprises a first cylindrical independently controllable gas volume and three concentric annular independently controllable gas volumes radially outward of the first cylindrical independently controllable gas volume. 
     
     
       7. The showerhead electrode assembly of  claim 1 , wherein a gas can be supplied to the independently controllable gas volumes of the heat transfer plate selected from helium, neon, argon, nitrogen, or a mixture thereof. 
     
     
       8. The showerhead electrode assembly of  claim 1 , further comprising at least one sensor, the at least one sensor configured to determine a temperature gradient across a plasma exposed surface of the showerhead electrode during use thereof. 
     
     
       9. The showerhead electrode assembly of  claim 1 , wherein each of the independently controllable gas volumes may be pressurized in a range of about 0 torr to about 1 atm. 
     
     
       10. The showerhead electrode assembly of  claim 1 , wherein each of the independently controllable gas volumes may be pressurized in a range of about 0 torr to about 10 torr. 
     
     
       11. A capacitively coupled plasma processing apparatus comprising:
 a vacuum chamber; 
 a lower electrode assembly adapted to receive a semiconductor substrate; 
 the showerhead electrode assembly of  claim 1 ; 
 at least one vacuum port in a bottom wall connected to at least one vacuum pump operable to maintain the vacuum chamber at a predetermined vacuum pressure; 
 a gas source operable to supply process gas through the showerhead electrode assembly to the vacuum chamber; and 
 an RF energy supply configured to energize the process gas into a plasma state. 
 
     
     
       12. The capacitively coupled plasma processing apparatus of  claim 11 , wherein the heat transfer plate is disposed between the top plate and the heater plate or the heat transfer plate is disposed between the heater plate and the showerhead electrode. 
     
     
       13. The capacitively coupled plasma processing apparatus of  claim 11 , wherein the independently controllable gas volumes of the heat transfer plate have a radial configuration, a non-radial configuration, a hexagonally divided configuration, an octagonally divided configuration, or a quadrant divided configuration. 
     
     
       14. The capacitively coupled plasma processing apparatus of  claim 11 , wherein the heat transfer plate comprises sixteen radially extending independently controllable gas volumes wherein eight gas volumes are located in an inner region of the heat transfer plate and eight gas volumes are located in an outer region of the heat transfer plate, each independently controllable gas volume extending about 38 to 45° around the circumference of the heat transfer plate. 
     
     
       15. The capacitively coupled plasma processing apparatus of  claim 11 , wherein the heat transfer plate comprises a first cylindrical independently controllable gas volume and three concentric annular independently controllable gas volumes radially outward of the first cylindrical independently controllable gas volume. 
     
     
       16. The capacitively coupled plasma processing apparatus of  claim 11 , wherein each of the independently controllable gas volumes may be pressurized in a range of about 0 torr to about 1 atm. 
     
     
       17. The capacitively coupled plasma processing apparatus of  claim 11 , wherein each of the independently controllable gas volumes may be pressurized in a range of about 0 torr to about 10 torr. 
     
     
       18. The capacitively coupled plasma processing apparatus of  claim 11 , further comprising at least one sensor, the at least one sensor configured to determine the temperature gradient across a plasma exposed surface of the showerhead electrode during use thereof. 
     
     
       19. A method of etching a semiconductor substrate in a capacitively coupled plasma processing apparatus using the capacitively coupled plasma processing apparatus of  claim 11 , comprising:
 placing a semiconductor substrate on a top surface of the lower electrode assembly inside the vacuum chamber; 
 pressurizing each independently controllable gas volume in the heat transfer plate comprised in the showerhead electrode assembly to a predetermined pressure to effect a desired temperature profile across the plasma exposed surface of the showerhead electrode; 
 measuring at least one temperature across the plasma exposed surface of the showerhead electrode; 
 adjusting in-situ the pressure in each independently controllable gas volume to compensate for temperature gradients across the plasma exposed surface of the showerhead electrode; 
 supplying a gas into the vacuum chamber from a gas supply; and 
 energizing the gas into a plasma state and etching the semiconductor substrate with the plasma. 
 
     
     
       20. The method of  claim 19 , further comprising measuring the temperature gradient across the plasma exposed surface while etching, and adjusting in-situ the pressure in each independently controllable gas volume to effectuate more uniform etching by reducing temperature gradients along the plasma exposed surface of the showerhead electrode.